practical wireless số 2008 09

R 33 September 2008 £3.50 ISSN 0141-0857 NOW IN NOW IN ITS 76th ITS 76th YEAR!YEAR! Build The 198kHz Off-air Frequency Standard Doing it by Design Comet CMX2300 Twin Cross SWR Power Meter Reviewed ● RF Power Measurements ● What Next? Practical Antenna Considerations ● In Focus The Coventry Amateur Radio Society ● Fun on 10 Metres! Build a 28MHz Antenna ● In the Shop With Harry Leeming ● A 3-Element Yagi Model versus practical test Practical Wireless September 2008 contents Volume 84. Number 9. Issue 1217. On sale 14 August 2008 Practical Wireless, September 2008 5 Copyright © PW PUBLISHING LTD. 2008. Copyright in all drawings, logos, photographs and articles published in Practical Wireless is fully protected and reproduction in whole or part is expressly forbidden. All reasonable precautions are taken by Practical Wireless to ensure that the advice and data given to our readers are reliable. We cannot however guarantee it and we cannot accept legal responsibility for it. Prices are those current as we go to press. Published on the second Thursday of each month by PW Publishing Ltd., Arrowsmith Court, Station Approach, Broadstone, Dorset BH18 8PW. Tel: 0845 803 1979. Printed in England by Holbrooks Printers Ltd., Portsmouth P03 5HX. Distributed by Seymour, 86 Newman Street, London , W1P 3LD, Tel: 0207-396 8000, Fax: 0207-306 8002, Web: http //www.seymour.co.uk. Sole Agents for Australia and New Zealand - Gordon and Gotch (Asia) Ltd.; South Africa - Central News Agency. Subscriptions INLAND £38, EUROPE £47, REST OF WORLD £57, payable to PRACTICAL WIRELESS, Subscription Department. PW Publishing Ltd., Arrowsmith Court, Station Approach, Broadstone, Dorset BH18 8PW. Tel: 0845 803 1979. PRACTICAL WIRELESS is sold subject to the following conditions, namely that it shall not, without written consent of the publishers first having been given, be lent, re-sold, hired out or otherwise disposed of by way of trade at more than the recommended selling price shown on the cover, and that it shall not be lent, re-sold, hired out or otherwise disposed of in a mutilated condition or in any unauthorised cover by way of Trade, or affixed to or as part of any publication or advertising, literary or pictorial matter whatsoever. Practical Wireless is Published monthly for $50 per year by PW Publishing Ltd., Arrowsmith Court, Station Approach, Broadstone, Dorset BH18 8PW, Royal Mail International, c/o Yellowstone International, 87 Burlews Court, Hackensack, NJ 07601. UK Second Class Postage paid at South Hackensack. Send USA address changes to Royal Mail International, c/oYellowstone International, 2375 Pratt Boulevard, Elk Grove Vi lage, IL 60007-5937. The USPS (United States Postal Service) number for Practical Wireless is: 007075. 6 Keylines Rob Mannion G3XFD discusses the preparation and submission of news items for PW. 7 Readers’ Letters Just the place to air your opinions and comments! 10 News A selection of news and product information of interest to Radio Amateurs. 17 Equipment Review Tex Swann G1TEX, the PW T echnical Editor , has been trying out the new Comet CMX2300 Twin- meter h.f and v.h.f. VSWR/Power meter. Read Tex’s report for the full story! 18 Club News The PW round-up of the club news scene. 20 Speech Processing – The How & Why! Ted Rule G3FEW takes a hard look at speech processing . Readers may think twice about using the processor after reading T ed’s article! 21 Rally Round-Up Fancy an Amateur Radio Day out? Plan your trip here and support rally organisers. 22 In Focus – The Coventry Amateur Radio Society . Join Bob Nash G4GEE – Chairman of the CARS – as he describes their activities and extends a welcome to anyone wishing to join this very active club. 26 Doing it By Design Tony Nailer G4CFY concludes his design work in Part 2 of the Off Air F requency Standard that uses the BBC 198kHz transmissions from the Droitwich tranmitter in Worcstershire. It’s a project that’s given Tony much pleasure! 31 Morse Mode Join Roger Cooke G3LDI as he shares his enjoyment using Morse. Despite The Times suggesting ‘Morse is dead’ – Roger knows it’s alive and well on the Amateur bands! 35 Antenna Workshop David Butler G4ASR describes a halo antenna suitable for 50MHz. This practical antenna has been around for years – but David suggests you try one on 6m. 38 Fun On 10m! In Part 2 of his detailed look at 28MHz operations, Roger Lapthorn G3XBM offers his own version of a halo antenna for 28MHz called the Home -Base 10 that ’s been very successful with the G3XBM low power DX-chasing. 42 A 3-Element Yagi Antenna & A P ractical T est Andy Foad G0FTD can’t resist a challenge! This time he coaxed a scrap Band II v .h.f. Yagi antenna onto the 144MHz band and obtained some good results. 46 VHF DXer Join David Butler G4ASR as he concentrates on chasing the exciting DX above 30MHz and collating your reports. 50 Carrying on The Practical W ay Classics While the Rev. George Dobbs G3RJV is moving home after his retirement he’s selected some classic articles for your pleasure. This month George takes the terror out of toroids! 52 What Next? This month Colin Redwood G6MXL discusses the various methods of erecting antennas, feeders and keeping them ‘up there’ safely with regular maintenance. 56 Making RF P ower Measurements Colin McEwen G3VKQ discusses the techniques he uses to measure radio frequency power on Amateur Radio frequencies and at commonly used power levels. 59 In The Shop This month Harry Leeming G3LLL discusses driver valves – and the diffi culties of identifying and replacing them, opportunistic thieves and Amateur Radio Vicars! 62 Valve & Vintage This month – perhaps surprisingly – Phil Cadman G4JCP is concentrating on those three legged things we call transistors as they ’ve been around for longer than we may realise. 68 HF Highlights Join Carl Mason GW0VSW as he presents readers’ reports from their last month ’s operations. 72 T raders’ Tables 74 Classifi ed Adverts 75 Bargain Basement 76 PW Publishing Bookstore 80 Subscriptions 81 Topical Talk Rob Mannion G3XFD comments on his own travel experiences and suggests that security at Britain ’s airports may have been compromised by the ‘Politically Correct’ (PC) approach shown towards immigrant minorities visiting or resident in the UK. Front cover: Our thanks go to Tex Swann G1TEX for the Comet SWR/Power meter and the G4CFY Off Air Frequency Standard photographs and the design by Steve Hunt. Practical Wireless, September 2008 6 E veryone involved with PW is acutely aware of the essential job that our news pages do for our widespread readers. However, as Editor I realise that we aren’t yet providing the best news service possible – although producing the news is a team job and readers can be part of that team! Recently, during separate club visits I was pleased and dismayed at the same time to hear from two different club chairmen that they regarded that the ‘art of communications’ within the hobby ‘were at a new low’. They were both disappointed at the poor level of contact between clubs themselves and also with the wider world. Although I was saddened at the news, it’s a long standing situation and I was pleased that such prominent Radio Amateurs were fully aware of the problems. Doing Something! As readers will know, I don’t raise a problem without also suggesting that we can do something about it. And we can do something! First, by working together we can help to ensure the news and information coming from our own clubs can be used effectively and isn’t just a jumbled set of notes that can confuse an Editor! It’s not diffi cult and the PW team will help anyone acting as a news source in every way possible to help promote the hobby. Nowadays, one of the most time consuming problems I have as a journalist is trying to make the best of a news story that’s bereft of vital information. Even modern E-mail and the Internet can’t help us out in many cases because, even though we make it clear that we can’t usually spare the time to accept the the common invitation to ‘please visit our website for news’, when I have been forced to ‘visit the website’ – the information required still isn’t available! So, to help I’ll provide a few points that can help us to produce the best quality and most accurate news story involving your club, group or activity in Amateur Radio. However, if further help is required the PW Author’s Guide (full of helpful suggestions for article writing) is now available in PDF form for E-mailing. The list of problems includes: Photographs of groups with no names, or without clear identifi cation, or with Christian/Given names and callsign only, omitting surnames (an essential courtesy to the person I believe). Often, we then fi nd that callsigns with no identifying surnames are listed as ‘Details Withheld’ in callsign directories! If a fi rst name and callsign only is provided for personal security reasons I can understand the requirement. However, as there’s no point revealing someone’s identity via a news item, I’ll support the requirement by not mentioning the individual in the report. When a news item is sent to us please try an ensure we have full contact details, including a daytime ‘phone number. It’s also important that your club knows you’re in contact with PW, because recently we published a news item – in good faith – only to have a senior member of the club asking where we’d got the information from! Fortunately, it was due to (well- meant) confusion. The vast majority of news stories come from reliable sources and I rarely have doubts. But you can help us with as much information as you can and together we’ll promote the hobby effi ciently! Video Documentaries I’ve recently been enjoying the excellent GPO documentaries available from www. lovefi lm.com I can thoroughly recommend those from the 1930s where Wick Radio and Aberdeen trawlers are featured in a simulated rescue. The equipment and radio procedures are delightful to see in action! One fi lm featured a Hebridean Island and the commentary announced that, “a young man is seen, using the hand operated telegraph machine to send orders to the mainland.” The machine was small and canister shaped with an operating crank handle on one side. Around the circumference at the top were a row of buttons associated with letters and numerals, which he pressed as an arm rotated. The machine seemed to be some form of an auto-keyer (perhaps with an Amateur Radio application?) and I’ll be fascinated to learn more about the device from an informed reader! Rob Mannion G3XFD/EI5IW Subscriptions Subscriptions are available at £38 per annum to UK addresses, £47 Europe Airmail and £57 RoW Airmail. See the Subscriptions page for full details. Components For PW Projects In general all components used in constructing PW projects are available from a variety of component suppliers. Where special, or difficult to obtain, components are specified, a supplier will be quoted in the article. Photocopies & Back Issues We have a selection of back issues, covering the past three years of PW. If you are looking for an article or review that you missed first time around, we can help. If we don’t have the whole issue we can always supply a photocopy of the article. See the Book Store page for details. Placing An Order Orders for back numbers, binders and items from our Book Store should be sent to: PW Publishing Ltd., Post Sales Department, Arrowsmith Court, Station Approach, Broadstone, Dorset BH18 8PW, with details of your credit card or a cheque or postal order payable to PW Publishing Ltd. Cheques with overseas orders must be drawn on a London Clearing Bank and in Sterling. Credit card orders (Access, Mastercard, Eurocard, AMEX or Visa) are also welcome by telephone to Broadstone 0845 803 1979. An answering machine will accept your order out of office hours and during busy periods in the office. You can also FAX an order, giving full details to Broadstone 01202 659950. The E-mail address is bookstore@pwpublishing.ltd.uk Technical Help We regret that due to Editorial time scales, replies to technical queries cannot be given over the telephone. Any technical queries by E-mail are very unlikely to receive immediate attention either. So, if you require help with problems relating to topics covered by PW, then please write to the Editorial Offices, we will do our best to help and reply by mail. Rob Mannion’s keylines Rob discusses something here Practical Wireless PW Publishing Limited Arrowsmith Court Station Approach BROADSTONE Dorset BH18 8P W Directors: Roger Hall & Stephen Hunt Editor Rob Mannion G3XFD/EI5IW rob@pwpublishing.ltd.uk T echnical Editor NG (Tex) Swann G1TEX/M3NGS tex@pwpublishing.ltd.uk Art Editor Stephen Hunt steve@pwpublishing.ltd.uk Advertising T ypesetting/Admin P eter Eldrett peter@pwpublishing.ltd.uk Advertisement Sales Roger Hall G4TNT roger@pwpublishing.ltd.uk Finance Manager Alan Burgess alan@pwpublishing.ltd.uk Book Orders bookstore@pwpublishing.ltd.uk T el: 0845 803 1979 F ax: 01202 659950 PW Publishing Website www.pwpublishing.ltd.uk Our 0845 numbers are charged at the BT Stand- ard local R ate Subscription Administration W ebscribe P ractical Wireless Subscriptions PO Box 464 Berkhamsted Hertfordshire HP4 2UR , UK pw@webscribe.co.uk www .mysubcare.com ☎ 01442 879097 F ax: 01442 872279 Shannon Airport Problems Dear Rob, Following my most recent visit to Ireland, I thought you and PW readers would be interested to learn of my experience when fl ying out of Shannon Airport in June with my Amateur Radio v.h.f. hand-held transceiver. As you know, I’m also a very frequent visitor to Ireland – and additionally – I’ve visited many other countries with Amateur Radio equipment including most European countries, Brazil, South Africa, Canada and the USA to name a few and I’ve never encountered any problems whatsoever. Normally when passing through airport security checks, it’s my small magic props that draw the attention of offi cials. However, when leaving Ireland via Shannon Airport recently, after my cabin baggage was X-rayed, I was pulled over to have all the items in it examined by hand. What seems to have caught the eye of the X-ray operator was my Amateur Radio v.h.f. hand-held. Even though I was carrying the front sheet of my on-line Amateur licence document, I was quizzed in great detail as to the type of radio, did it transmit, was it used for receiving only, what frequencies did it cover and why did I need it to visit Ireland? The offi cial then intimated that he would have to seek further advice from his manager, so off he went with my licence and radio leaving me to repack my bag. After about ten minutes he returned and clearly in a less belligerent and offi cial mood. It transpired that while talking about the radio to his manager in the offi ce, a member of staff who was a Radio Amateur (offi cially we are ‘Experimenters’ in Eire) gave my radio and licence a cursory check and declared all was well. This of course begs the question that if there had not been a member of staff who was a Radio Amateur to vouch that I was Radio Amateur with a genuine reason for carrying a hand- held with me, would my radio have been confi scated? It would be interesting to know if any PW readers in Eire have encountered similar diffi culties when fl ying out of Irish airports carrying Amateur Radio equipment? Colin Topping GM6HGW Glenrothes Fife Scotland Editor’s comment: Colin’s reference to ‘magic props’ is due to his actvities as a member of the Magic Circle. To ensure we can publish the full facts I contacted the management at Shannon Airport and it was some time before a reply was forthcoming. After reading the reply from the Shannon management I invite readers to join me on the Topical Talk pages where I share my own experiences and observations. Rob G3XFD. Letter From Colin Topping Dear Sir, Reference the E-mailed letter from Colin Topping. I apologise for our delayed response to your letter received in early June, in respect of Colin Topping’s recent experience at Shannon Airport. As you can appreciate, from a security perspective once an electronic and/or battery operated device is detected at any airport screening facility it is subject to additional examination. This is so an X-Ray screening offi cer can satisfy himself / herself that such items are not a threat and operate as intended. In this instance the screening offi cer brought the v.h.f. hand held transceiver to the attention of his supervisor to ensure that it complied with EU security regulations. Practical Wireless readers’ letters The Star Letter will receive a voucher worth £20 to spend on items from our Book Store or other services offered by Practical Wireless. Practical Wireless, September 2008 7 Ken Smith G3JIX’s Article Dear Rob, With reference to Ken Smith G3JIX’s article entitled Amateur Radio Exams & Licences on page 54 of the July edition of Practical Wireless. Modern youngsters taking up radio? How do we do that – have PW readers got any ideas? – well I offer a possible solution to this problem. I currently work as a part time lecturer at a local Further Education College teaching on the EAL course www.eal.org.uk The syllabus for the course is divided into three parts. Panel wiring, Electrical installation, and Electronics. The course is designed to give students a wide range of skills, both theoretical and practical. The Panel wiring and Electrical installation parts of the course are very much laid in tablets of stone and don’t leave much scope for alteration. However, the electronics part of the syllabus is open to wide interpretation. As a Radio Amateur I have suggested introducing radio as the theme for the electronics part of the course. Students would start by making a crystal set, moving quickly on to building an amplifi er for the crystal set, which can then be used as part of a radio receiver and so on. It’s hoped that the fi nal project for the year will be a superhet radio. Students will be encouraged to build radio projects using various methods breadboard, stripboard, and p.c.b.s. One of the problems that will be encountered is that of sourcing and supply, particularly for coils. By introducing a radio theme it is hoped students will be motivated to learn. Students will also be allowed to take some of the projects home to experiment with, hopefully motivating them further in the art of radio. If there are any other PW readers or college lecturers teaching on this or similar courses I would be interested to know. I would also be grateful if anyone can help with the sourcing and supply of components for this course. Brian Parker G4EFW Sutton Coldfi eld West Midlands Star LetterStar Letter Send your letters to: Rob Mannion, PW Publishing Ltd., Arrowsmith Court, Station Approach, Broadstone, Dorset BH18 8PW E-mail: pwletters@pwpublishing.ltd.uk Practical Wireless, September 2008 8 readers’ letters For future reference I would suggest that where a passenger is carrying an unusual electronic and /or battery operated device in their hand baggage, it should be declared in advance of the screening point similar to the way that laptops are presented. This would assist the screening offi cer in making a quicker assessment of the item being carried. If diffi culties are encountered by passengers with such items we would recommend that the assistance of a Screening Supervisor be requested. There was never any question of this item being confi scated, but as your readers will appreciate, security is paramount and screening personnel need to satisfy themselves of the bona fi de of items being presented. Yours sincerely Niall Maloney Head of Operations & Services Shannon Airport County Clare Republic of Ireland Roy’s Accident Dear Rob, Since I was a ‘Brat’ have always been a proponent of mobile and portable communications. That interest has survived through professional operating, CB, and Amateur Radio operating to the present day. I cannot think of a car I have owned which didn’t at some time sprout at least one antenna and I rarely go out without a hand-held transceiver tuned to the local repeater. However, as a result of two signifi cant recent events I will be changing my attitude to ‘in car entertainment’ but the hand-held radio will still stay close to ‘hand’. Recently, I was the innocent victim of a road traffi c accident. I was crossing the road on a Zebra crossing when a van ran into the rear of the vehicle that had stopped to let me pass. The result was damage to the van, car and personal injuries to myself and the driver of the van has been charged with driving without ‘Due Care and Attention’. I can confi rm that suffering injuries, and waking up, somewhat surprised, with post traumatic amnesia, on a hospital trolley half an hour later has had a profound effect on me! The second seminal event is a recent report in the national press of a driver being jailed for causing an accident when using a Blue-tooth telephone. His attention was distracted, he failed to appreciate that the traffi c ahead had come to a standstill, and he impacted another vehicle. A passenger in one of the stationary vehicles was killed. There but for the grace of God go many of us! I know that the Amateur fraternity have a ‘Free Pass’ when it comes to using mobile radio, as opposed to cell phone equipment. No doubt that concession was hard won by well meaning people but make no mistake, it’s not a ‘Get out of Jail Free’ card. Anyone who allows operation of their Amateur equipment, Bluetooth or not, to detract from the normal standard of driving care make themselves liable to prosecution. And – if the current case is a precedent – to imprisonment. So, my antennas remain on the vehicle, ‘just in case’ although the radio equipment now lives in a case, in the boot, ready for use ‘static mobile’ from a fi xed, parking spot when required. I would seriously urge fellow operators to adopt a similar attitude. Yes, it could be viewed as an infringement of our legislated rights; but balance that against the possibility of a term of imprisonment, or the memory of wiping out an innocent victim. Roy Walker G0TAK Kendal Cumbria Editor: A timely warning Roy! Everyone on PW – and I’m sure readers also – wish you a speedy and good recovery. Rob G3XFD. Trimming Dipoles? Dear Rob, With reference to the letter by Graham Hart M0EAD, Trimming Dipoles? in the August issue of PW and I must stress that there is a great deal of confusion about matching antennas. First – a (so called) antenna tuner unit does not tune the antenna. It only provides a way to match whatever impedance is at the transmitter end of the feeder to the transmitter. An indicated low v.s.w.r. only means that the transmitter is then matched to whatever is ‘seen’ at the end of the feed line. If the actual antenna was originally mismatched to the feed line, it is still mismatched ! The standing wave ratio along the feeder is dependent entirely on the load presented at the antenna end, and no amount of alteration at the transmitter end can alter the actual s.w.r. Take an example of where the s.w.r. is 2:1 due to a mismatched antenna. The s.w.r. meter at the transmitter will show 2:1 (assuming no loses in the feeder system). Using an a.t.u. to reduce this to 1:1 at the transmitter will not change the actual s.w.r. and a second s.w.r. meter placed in circuit between the a.t.u. and feeder will still show that it’s 2:1. However, matching the transmitter in this way will ensure that (with a transistor rig) the p.a. is protected and also delivering its full power output to the antenna system. However, a 2:1 s.w.r. means that some of the transmitted power arriving at the antenna end of the feeder is being refl ected back down to the transmitter end. As this is mismatched, some of that is refl ected back up to the antenna – being either dissipated in the feeder line losses or by radiation. This loss is why a ‘lossy’ coaxial cable will show less s.w.r. than a low-loss cable. In other words, if you improve the quality of the coaxial cable used you may well fi nd the s.w.r. has increased! What is the effect of this high s.w.r. in practice? In an effort to fi nd out I set up a remote r.f. indicator to measure the radiation from my antenna. Starting at the resonant frequency of the antenna on 80m the s.w.r. was 1.05:1 without an a.t.u I set the r.f. indicator to read full scale. Changing frequency to get an indicated s.w.r. of 2:1 the r.f. indicator showed only a very small reduction in radiation. I then used an a.t.u. (an AT230) to adjust the s.w.r. to 1:1, the indicated radiation dropped slightly more! Most likely due to losses in the a.t.u Checking at both band edges showed the same results. Only when the s.w.r. was higher than 3:1 did my a.t.u. show an improvement in the radiated signal. A s.w.r. up to 3:1 seems to have little effect on the radiated signal. In fact the introduction of the a.t.u. showed a loss of about 0.5dB in radiated power ! These fi ndings should not be taken as conclusive but were unexpected and seem to indicate that we may worry far too much about high s.w.r. It should also be noted that the feed impedance of a antenna will vary with height above ground. For example a half wave dipole on 3.7MHz at a height of 12 metres, drops to around 26Ω. But, by tuning slightly to one side of resonance I found It possible to fi nd a point where it is 50 or 75Ω and appear to get a 1:1 s.w.r Ted Rule G3FEW Lenwade Norfolk Practical Wireless, September 2008 9 Part Exchange & Martin Lynch Dear Rob, I read with interest the letter from Tony Corbett G0WFV regarding part exchange and Martin Lynch’s reply. However, one thing Martin didn’t mention is that retailers have also to add VAT on to their re-selling price. (Yes the Chancellor gets two, or more, bites of the VAT cherry!) which I think is outrageous! Another way of selling used equipment that Lowe Electronics of Matlock used to offer was a service called ‘Sold on behalf of’ where the person offering the equipment sets the asking price and Lowe added a small commission for offering the shelf space in their showroom. This way there was no additional VAT to charge as it remained a ‘Private sale’. They also offered, for an additional charge to the buyer, a full testing service so that the buyer could at least be aware of any problems that there was (if any) with the equipment before deciding to buy or not. Regarding re-sale prices of used Amateur Radio equipment, I noticed that during the 1980s and 1990s we could get very good returns on used equipment as long as it was in very good (as new) condition and with all original packaging, manuals, accessories, etc., but these days this seems no longer to be the case. I think that this could be that manufacturers seem to bring out newer and updated versions of their existing products with ever decreasing time intervals and therefore ‘current’ models don’t stay current for very long! Regards to you all and keep up the good work with PW. John Blain G4SKU Flitwick Bedfordshire Part Exchanging Equipment Dear Rob, I would not want to take sides in the discussion regarding part-exchange and trade-ins of equipment, but I would like to mention a problem, which I experienced in such instances when running my own business (not radio related). If I part-exchanged or traded- in customer’s goods for, say, £100 and wished to make a profi t of £15, the selling price would be £135.13. Why? Because I had to add VAT, amounting to £20.13, to the whole selling price, and this element went straight to Customs & Excise (now HMRC). My regards. Nick Hockenhull MW6NCH Summerhill Pembrokeshire Editor’s comment: My thanks go to to both John G4SKU, Nick MW6NCH and other readers for pointing out the imposition of VAT on secondhand equipment sales by the ever greedy Chancellor of the Exchequer! Martin Lynch and I thank you all for the reminders! Rob G3XFD. Contests & Exhanges Dear Rob, As a sometime participant in contests and now the Adjudicator of the Practical Wireless 144 MHz QRP contest, I read Dave Ackrill G0DJA’s letter in the July issue of PW regarding contests (amongst other things) with some interest. In replying I fi rst put myself in the shoes of a station actively participating in the contest. The rules of many contests state that the contest exchange includes reports and serial numbers. Therefore participating stations will be expecting to exchange this information. Until a participating station is satisfi ed that the non-participating station is actually non-participating, I think it’s reasonable to expect that in contacts with a contest station (who, in most cases. will have clearly indicated this by calling “CQ Contest”) the contest station will expect to receive the information required for the contest exchange. Failure to do so, and record the information accurately risks a deduction of points, and in the spirit of ‘fair-play’ most participants would want to satisfy themselves the both stations had successfully received the exchange from each other. In weak signal situations actually conveying that you are not participating in the contest might be a bit of a challenge without inventing a new ‘Q’ code! Speaking frankly, I think that – in such situations – giving a serial number of 001 is probably the quickest way to enable both parties to complete a contest QSO and move on to QSOs with other stations. However, putting myself into the Adjudicator’s shoes, serial numbers exchanged are vital pieces of information. No matter whether logs are cross-checked manually or electronically (or any mixture of the two), the callsigns together with serial numbers are the easiest way to fi nd QSOs for checking purposes – hence they are part of the exchange in most contests including the Practical Wireless 144 MHz QRP Contest. Whilst I will accept that callsigns and time could be used, the reality is that people don’t log time particularly accurately, especially when operating portable. Callsigns and serial numbers are absolutes – either they match or they don’t! In addition serial numbers are the only pieces of genuinely unknown and un-guessable information in a contest exchange. Check logs are typically submitted by stations that made a few contacts during a contest, wanted to submit a log, but were ineligible to enter the contest, perhaps because they running more power, were operating portable in fi xed contest, or perhaps only operated for a short time and didn’t want to be bottom of the results table, etc. A good checklog with serial numbers will be used by the Adjudicator in virtually the same way as a contest entry apart from appearing in the table of results. Whilst all checklogs are welcome and helpful to Adjudicators, the usefulness of one without serial numbers to my mind is limited. The adjudicator will have lots of extra work to make use of it in comparison to one with properly sequential serial numbers. Finally, if someone were to ask me, “Colin, would you deduct points from an entrant who had logged a serial number of 001 from a contact from a non-competing station that submitted a check log which had no serial numbers?” – my answer would be a defi nite ‘No!’ Colin Redwood G6MXL Poole Dorset A great deal of correspondence intended for ‘letters’ now arrives via E-mail, and although there’s no problem in general, many correspondents are forgetting to provide their postal address. I have to remind readers that although we will not publish a full postal address (unless we are asked to do so), we require it if the letter is to be considered. So, please include your full postal address and callsign with your E-Mail. All letters intended for publication must be clearly marked ‘For Publication’. Editor Obituary Air Marshal Sir Eric Dunn KBE CB BEM CEng RAF, G3KED Patron of the Royal Air Force Amateur Radio Society, died on the 16th July 2008 at the age of 80. Eric Dunn started his Air force career at the age of 16 when he joined the Air Force as an Aircraft apprentice. He trained at No.1 Radio School, then at RAF Cranwell, and graduated after three years as a radio fi tter (Air). Throughout his distinguished Air Force service he was a keen sportsman. After 42 years he had risen to the rank of Air Marshal and was the RAF’s Chief Engineer. During the Falklands Confl ict he served as Air Offi cer Engineering at HQ Strike command and shortly after the campaign he visited the Islands to assess the Air Arm’s requirements. Air Marshal Dunn followed in the steps of his father in more than one way. Dunn senior was a Wing Commander in the RAF and a keen Radio Amateur. Sir Eric was licensed as G3KED and retained a keen interest in the hobby, and, as Patron of RAFARS he assisted the Society and visited them whenever it was possible. The photograph was taken on his last visit to RAFARS HQ at RAF Cosford. Roy Walker G0TAK. N eil Tideswell 2E0BHS and friends will be riding their motorcycles around the entire UK coast to raise money for the Assert (B&H) charity, which was set up to help people in Sussex with Asperger’s syndrome. One of the other riders, Dominic O’Doherty, is himself a sufferer and Assert (B&H) helped him to get his motorcycle licence and now he is studying to become an M3. Going Coastal will start in Brighton at noon on Sunday, 17th August and fi nish some 22 days and more 3,400 miles later on Sunday, 7th September, again in Brighton. If you’d like to follow Neil on his travels, he will be on the air to give progress reports throughout the journey. He plans to use the IC-7000 loaned by Icom UK and the Outbacker Joey mobile HF antenna loaned by Adur Communications to transmit every evening at 19.00 (UTC) on 80m (3.650MHz ± 20KHz). During the day he will be using 2m (145.525MHz ±) to keep in touch. If you want to know more about Going Coastal, their website is at: www.goingcoastal.org.uk Assert (B&H) have a site at: www.assertbh.org.uk Practical Wireless, September 2008 10 McMichael Rally Winner A day out to the McMichael Rally on Sunday July 12th was really worthwhile for Andrew Birch M0YGB – he won the Yaesu FT-450AT worth £600 in the grand raffl e. Andrew’s prize was donated by Yaesu UK and Martin Lynch & Sons. The popular event, held at Reading Rugby Football Club in Sonning-on-Thames drew many visitors but Andrew – from High Wycombe – had luck on his side! Martin Lynch G4HKS (right) presents the Yaesu FT-450AT to lucky winner Andrew Birch M0YGB, with Rally Chairman Min Standen G0JMS on the left. Photo courtesy Martin Lynch & Sons Ltd. Going Coastal A Message From Hans Hilberling Stop Press News! The following announcement was posted on the Hilberling company’s website in late July. Everyone who saw the full display of the company’s equipment at the recent Friedrichshafen Hamfest will be saddened to hear of the company’s problems. The original notice was published in German and I hope that no errors have crept into my translation. Editor. “I regret to announce today that Hilberling GmbH has cancelled the production of the PT-8000 series of transceivers. I am really sorry that this will cause disappointment on your side. Let me explain briefl y what had led to this decision. Hilberling had to continuously counteract obstacles to meet EU wide requirements. This has forced us (many times) to change the design of this high-end transceiver, which often has been in confl ict to our design goals. We fi nally could meet all our design numbers within a few prototypes but we – and the numerous suppliers – were not able to guarantee these numbers for the line production. Measures that would have to be taken to guarantee the specifi cations are in no way cost effective. All this has led to the decision to put everything on hold. Hilberling apologises for any inconvenience you had. We deeply appreciated the confi dence you demonstrated for the PT-8000 series of h.f./v.h.f. transceivers. Hans Hilberling July 24th, 2008 Practical Wireless Newsdesk news & products A comprehensive round-up of what’s happening in our hobby. Air Marshall Eric Dunn G3KED. [...]... 10MHz 74HC04 ÷ 5 7 ÷ 5 12 ÷ 2 13 ÷ 2 ÷ 5 1 7 200k 20k 10MHz 2M 26 2k ÷ 5 12 ÷ 2 13 ÷ 2 1 74HC74 1M 100k 10k 1k Practical Wireless, September 2008 Fig 2: The circuit diagram of the single p.c.b version of the OAFS Practical Wireless, September 2008 27 C34 10n 68k 2 74HC04 IC5:A R30 1 D3 BB 809 1n C35 LW coil L101 13 Vi 10MHz VC2 30p X1 74HC04 12 Gnd IC5:D Vo IC3 78L06 PIN J2 R32 39k R31 39k C24 10 VC1... £8 P&P But mention this review and Practical Wireless for free P&P on the meter Supplier Nevada Radio, Unit 1, Fitzherbert Spur, Farlington, Portmouth, Hampshire PO6 1TT Tel: 023 92131 3091 www.nevadaradio.co.uk Our Technical Editor ‘Tex’ Swann G1TEX, has taken a first look at a dual circuit power/Standing Wave Ratio (s.w.r.) meter unit Practical Wireless, September 2008 17 club news Please remember... welcome at meetings So, come along and join us! ● Practical Wireless, September 2008 Open six days a week Mon - Fri: 9.30am - 5.30pm Sat: 9.00am - 5.00pm Outline House, 73 Guildford Street, Chertsey, Surrey KT16 9AS Tel: 0845 2300 599 (Local Call Number) Tel: 01932 567 333 (Direct Dial Number) Web: www.hamradio.co.uk E-mail: sales@hamradio.co.uk WX-2008MkII Weather Station Everything you need is included... klarc.org.uk King’s Lynn Amateur Radio Club meets every Thursday at the Scout HQ, Chequers Lane, West Winch, King’s Lynn, PE33 0NY off the A10 at West Winch at 7.30pm Practical Wireless, September 2008 Norfolk ARC Mark Taylor Tel: (01362) 69 1099 E-mail: narc@g0lgj.co.uk www.norfolkamateurradio.org The Norfolk Amateur Radio Club meets every Wednesday at the Happy Landings, Norwich Aviation Centre, Norwich... 112-137cm long £279.95 plus £7.99 P&P (mobile mount shown available at £29.95) Callers welcome Opening times: Mon-Fri 9-6pm sales@moonrakerukltd.com CRANFIELD ROAD, WOBURN SANDS, BUCKS MK17 8UR Practical Wireless, September 2008 PICTURES ARE FOR REFERENCE ONLY PL259/9 plug (Large entry) £0.75 PL259/9C (Large entry) compression type fit £1.95 PL259 Reducer (For PL259/9 to conv to PL259/6) £0.25 PL259/6... Fitting: PL259 .£24.95 CALL MAIL ORDER 01908 281705 Opening times: Mon-Fri 9-6pm sales@moonrakerukltd.com UNIT 12, CRANFIELD ROAD UNITS, CRANFIELD ROAD WOBURN SANDS, BUCKS MK17 8UR 16 Practical Wireless, September 2008 Review This meter hit the right spot with Tex! Comet CMX2300 Twin Power and SWR meter O ne of the first pieces of test units that many Radio Amateurs need when setting up a station,... further information visit www.bletchleypark.org.uk or E-mail info@bletchleypark.org.uk or call (01908) 640404 Write to Bletchley Park Trust, The Mansion, Bletchley, Milton Keynes MK3 6EB Practical Wireless, September 2008 Send all your news to: PW Publishing Ltd., Arrowsmith Court, Station Approach, Broadstone, Dorset BH18 8PW E-mail: newsdesk@pwpublishing.ltd.uk New D-Star Repeaters in Dorset & Essex... museum houses the UK’s only fully-working cotton mill engine, complete with its original steam raising plant and 220ft high chimney Newcomers are always welcome and made to feel at home Practical Wireless, September 2008 LINCOLNSHIRE Eagle RG Eddie Lingard Tel: 01507 472695 E-mail: e.f.lingard@btinternet.com www.eagleradiogroup.com The Eagle Radio Group meets at The Eagle Hotel, Victoria Road, Mablethorpe... come from So that’s my story about what happened – I was rescued thanks to Amateur Radio, my friends and the Royal National Lifeboat Institution Thank you everyone.” Daniel Small MM3NMI Practical Wireless, September 2008 All At Sea Icom’s GB0RSR Special Station On The Red Sands Offshore Fort! R ecently, Icom UK launched GB0RSR the special event station based on the Thames Estuary Maunsell Army Sea Forts,... previous level For example, if at a distance of 150mm Ted Rule G3FEW – with many years on the Amateur bands – suggests that good microphone technique should come before speech processing 20 Practical Wireless, September 2008 (around 6in) the output is (say) 1V then at , about 76mm(about 3in) it will be 4V which , is a voltage ratio of 12dB Note: Power output from a transmitter is the voltage squared divided . Yagi Model versus practical test Practical Wireless September 2008 contents Volume 84. Number 9. Issue 1217. On sale 14 August 2008 Practical Wireless, September 2008 5 Copyright ©. regulations. Practical Wireless readers’ letters The Star Letter will receive a voucher worth £20 to spend on items from our Book Store or other services offered by Practical Wireless. Practical Wireless, . £57, payable to PRACTICAL WIRELESS, Subscription Department. PW Publishing Ltd., Arrowsmith Court, Station Approach, Broadstone, Dorset BH18 8PW. Tel: 0845 803 1979. PRACTICAL WIRELESS is sold